JP2006029638A - Radiant tube burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiant tube burner capable of improving efficiency of exhaust heat recovery of combustion gas and improving thermal efficiency. <P>SOLUTION: This radiant tube burner 1 has a heat exchange tube 5 arranged between a bulkhead 22 of a burner body 2 and an inner tube 4 to connect it in the axial direction of an outer tube 3. A second exhaust passage 82 is formed between the heat exchange tube 5 and the inner tube 4, and a third exhaust passage 83 is formed between the heat exchange tube 5 and the bulkhead 22. An exhaust gas communicating clearance 51 for communicating the second exhaust passage 82 and the third exhaust passage 83 mutually is provided in a rear end part in the axial direction of the heat exchange tube 5. A plurality of heat transmitting fins 45 are provided on an outer peripheral side of the inner tube 4 except a part in the vicinity of a rear end part in the axial direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiant tube burner for heating an atmospheric gas in a heat treatment furnace without directly contacting with a combustion gas.

  As shown in FIGS. 4 to 6, the combustion gas 102 by the burner nozzle 920 passes through the inside of the radiant tube 90 and the combustion gas 102 and the atmospheric gas 103 in the heat treatment furnace 6 are not brought into direct contact with each other, so that There is a radiant tube burner 9 that heats the inside of the heat treatment furnace 6 with radiant heat from the surface of 90. As an example, a radiant tube of a single end type configured by providing a burner body 92 having a burner nozzle 920 at one end of a radiant tube 90 having a double tube structure having an outer tube 3 and an inner tube 4 and sealing the other end. There is a burner 9.

  In the radiant tube burner 9, the combustion air 101 sucked from the intake port 923 is passed through the first intake passage 971 formed between the housing 921 of the burner body 92 and the partition wall 922. Then, the combustion air 101 is caused to flow from one end of the inner tube 94 to pass through a second intake passage 972 formed between the inside of the inner tube 94 and the burner nozzle 920, and injected from the burner nozzle 920. Burn with burned fuel.

Thereafter, the combustion gas 102 that has been burnt is connected to the first exhaust passage 981 formed between the inner tube 94 and the outer tube 93 from the other end of the inner tube 94, and the inner tube 94 and the partition wall 922. Then, the air is exhausted from the exhaust port 924 through the second exhaust passage 982 formed between the exhaust port 924 and the second exhaust passage 982.
When the combustion gas 102 passes, the combustion gas 102 flowing through the first exhaust passage 981 and the second exhaust passage 982 flows into the inner tube 94 with the inner tube 94 as a heat transfer surface. Exhaust heat from the combustion gas 102 is recovered by exchanging heat with the generated combustion air 101.

  Further, in the radiant tube burner of Patent Document 1, a cylindrical heat exchange tube is disposed between the partition wall of the burner body and the inner tube in order to improve the exhaust heat recovery efficiency of the combustion gas. An exhaust passage for allowing combustion gas to pass therethrough is formed between the heat exchange tube and the inner tube and between the heat exchange tube and the partition wall.

  By the way, in Patent Document 1, heat transfer from combustion gas to combustion air is performed by an inner tube and a partition wall. That is, the combustion air flowing in the inner tube exchanges heat with the combustion gas flowing in the first exhaust passage and the second exhaust passage using the inner tube as a heat transfer surface, and recovers exhaust heat from the combustion gas. The combustion air flowing in the intake passage of the burner body exchanges heat with the combustion gas flowing in the third exhaust passage using the partition wall as a heat transfer surface, and recovers exhaust heat from the combustion gas.

  However, both the inner tube and the partition wall have only a tube shape, and the radiant tube burner of Patent Document 1 is not sufficient for further improving the exhaust gas heat recovery efficiency. .

  Patent Document 2 discloses that the heat recovery capability is improved by providing a plurality of fins in the heat exchanger for preheating introduced air in the radiant tube for heat treatment furnace. However, Patent Document 2 assumes that burners are provided at both ends of the radiant tube, and fins are provided in a regenerative burner that alternately burns each burner. That is, in a single-end type radiant tube burner, it is necessary to supply combustion air and fuel and exhaust combustion gas in one burner body. Therefore, the technique of Patent Document 2 cannot be applied to a single-end type radiant tube burner as it is, and a device specific to the single-end type is required.

Japanese Patent Laid-Open No. 2003-307301 JP 7-305833 A

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a radiant tube burner capable of improving the exhaust gas heat recovery efficiency and improving the thermal efficiency.

The present invention includes a cylindrical housing having an intake port and an exhaust port, a cylindrical partition wall disposed on the inner peripheral side of the housing, and a gas pipe disposed on the inner peripheral side of the partition wall. Burner body,
An outer tube disposed on the outer peripheral side of the gas pipe and connected in the axial direction of the burner body;
An inner tube disposed between the gas pipe and the partition wall and the outer tube;
Combustion air taken in from the intake port is passed through a first intake passage formed between the housing and the partition, and is formed between the inner tube and the gas pipe from one end of the inner tube. The fuel is injected into the second intake passage and burned together with the fuel injected from the gas pipe, and the burned combustion gas is formed between the inner tube and the outer tube from the other end of the inner tube. In the radiant tube burner configured to pass through the first exhaust passage and lead to the exhaust port,
A heat exchange tube is disposed between the partition wall and the inner tube so as to be connected in the axial direction of the outer tube, and communicated with the first exhaust passage between the heat exchange tube and the inner tube. Forming a second exhaust passage, and forming a third exhaust passage communicating with the exhaust port between the heat exchange tube and the partition wall,
The heat exchange tube is formed with an exhaust communication gap that communicates the second exhaust passage and the third exhaust passage, and the exhaust communication gap is formed at the rear end of the heat exchange tube in the axial direction. It is formed in a part in the circumferential direction of the heat exchange tube, and is formed at a position opposite to the exhaust port,
The radiant tube burner is characterized in that a plurality of heat transfer fins are provided on the outer peripheral side of the inner tube except for the vicinity of the rear end portion in the axial direction.

The radiant tube burner of the present invention is formed by providing a heat exchange tube between the partition wall of the burner body and the inner tube, and in order to more efficiently recover the exhaust heat from the combustion gas, A plurality of heat transfer fins are provided on the outer peripheral side.
Further, the efficiency of recovering the exhaust heat is further increased by devising the formation state of the heat transfer fins and the formation state of the exhaust communication gap in the heat exchange tube.

That is, the exhaust communication gap is formed at the axial rear end of the heat exchange tube, and the heat transfer fins are provided except for the vicinity of the axial rear end on the outer peripheral side of the inner tube. Thereby, the combustion gas inflow space where the heat transfer fin is not provided is formed in the vicinity of the axial rear end portion on the outer peripheral side of the inner tube.
Further, the exhaust communication gap is formed in a part of the heat exchange tube in the circumferential direction, and is formed at a position opposite to the exhaust port in the burner body.

The exhaust heat recovery performed when the combustion gas passes through each exhaust passage will be described below.
That is, the combustion gas generated by the combustion of the fuel and the combustion air passes through the first exhaust passage, the second exhaust passage, and the third exhaust passage, and is exhausted from the exhaust port to the outside of the radiant tube burner. .

When the combustion gas passes through the first exhaust passage and the second exhaust passage, the combustion gas exchanges heat with the combustion air flowing in the inner tube with the inner tube serving as a heat transfer surface. The temperature of combustion air can be raised. At this time, the heat exchange between the combustion gas and the combustion air is further promoted by the plurality of heat transfer fins provided in the inner tube, and the exhaust gas heat recovery efficiency can be further improved.
Thus, as the first stage exhaust heat recovery, exhaust heat due to the combustion gas flowing in the first exhaust passage and the second exhaust passage can be recovered.

Next, the combustion gas subjected to the first stage exhaust heat recovery flows from the second exhaust passage to the third exhaust passage through the exhaust communication gap provided in the heat exchange tube. When the combustion gas that has undergone the first stage exhaust heat recovery passes through the third exhaust passage, the combustion gas exchanges heat with the combustion air that flows through the intake passage, with the partition wall serving as a heat transfer surface. The temperature of the combustion air can be increased.
Thus, as the second stage exhaust heat recovery, exhaust heat due to the combustion gas flowing in the third exhaust passage can be recovered.

Further, when the exhaust heat recovery at the first stage and the second stage is performed, the combustion gas flowing in the second exhaust passage is an unformed portion of the heat transfer fin after flowing along the heat transfer fin. The gas flows into the gas inflow space, and flows around the outer peripheral side of the inner tube to the exhaust communication gap using the gas inflow space. Therefore, the combustion gas flowing in the second exhaust passage along the heat transfer fins can smoothly flow to the third exhaust passage through the exhaust communication gap.
Further, the exhaust communication gap and the exhaust port are formed at positions opposite to each other in the circumferential direction, so that it is possible to prevent the combustion gas passing through the exhaust communication gap from being immediately exhausted to the exhaust port.

As described above, in the present invention, the heat exchange tube is provided to form the second exhaust passage and the third exhaust passage, so that the combustion gas hardly flows from the first exhaust passage toward the exhaust port. can do. And the exhaust heat recovery efficiency of the said combustion gas can be improved by performing the said 2 steps | paragraphs of exhaust heat recovery in the state which lengthened the residence time of the combustion gas in the said radiant tube burner.
Further, in the present invention, exhaust heat recovery efficiency can be further improved by devising the formation of the plurality of heat transfer fins described above, the formation state of the heat transfer fins, and the formation state of the exhaust communication gap in the heat exchange tube. .
Therefore, according to the present invention, the exhaust gas heat recovery efficiency can be improved, and the thermal efficiency of the radiant tube burner can be further improved.

A preferred embodiment of the present invention described above will be described.
The radiant tube burner according to the present invention can be used for fixing to the furnace wall of the heat treatment furnace and heating the atmospheric gas in the heat treatment furnace without contacting with the combustion gas.
And it is preferable to use the said radiant tube burner when heating the atmospheric gas in a heat treatment furnace to the temperature of 500-1300 degreeC. In this case, the high thermal efficiency can be realized without making the burner body too hot.

  The axial rear end of the inner tube can be attached to the axial rear end of the partition wall. Further, on the outer peripheral side of the inner tube, the range in the vicinity of the rear end portion in the axial direction where the heat transfer fin is not provided is, for example, 10 from the rear end in the axial direction of the heat exchange tube disposed opposite to the outer peripheral side of the inner tube. The distance can be in the range of ˜100 mm.

In addition, a gas nozzle having a diameter larger than that of the gas pipe is formed at the axial tip of the gas pipe, and the tip of the heat transfer fin in the inner tube is located near a position facing the gas nozzle. (Claim 2).
In this case, the combustion air passing through the second intake passage passes through the first exhaust passage and the second exhaust passage when the first stage exhaust heat recovery is performed using the inner tube as the heat transfer surface. Heat transfer fins can be provided in as many portions as possible to exchange heat with the gas. Therefore, the exhaust heat recovery efficiency in the first stage can be improved.

Hereinafter, embodiments of the radiant tube burner of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, the radiant tube burner 1 of this example is provided with a burner body 2 at one end of a double-tube radiant tube 10 having an outer tube 3 and an inner tube 4, and the other end is sealed. A single-end type radiant tube burner 1 configured as described above.
In the radiant tube burner 1 of this example, the heat exchange tube 5 is provided between the partition wall 22 of the burner body 2 and the inner tube 4. After the fuel 100 and the combustion air 101 are burned, The exhaust heat generated by the combustion gas 102 is recovered more efficiently.

That is, as shown in FIGS. 1 and 2, the radiant tube burner 1 includes a cylindrical housing 21 in which an intake port 23 for combustion air 101 and an exhaust port 24 for combustion gas 102 are disposed, It has a burner body 2 including a cylindrical partition wall 22 inserted and disposed on the peripheral side, and a gas pipe 20 inserted and disposed on the inner peripheral side of the partition wall 22. Further, the radiant tube burner 1 has an outer tube 3 and an inner tube 4.
The outer tube 3 covers the outer peripheral side of the gas pipe 20 and is connected in the axial direction of the burner body 2. Further, the inner tube 4 covers the outer peripheral side of the gas pipe 20 and is inserted into the inner peripheral side of the partition wall 22 of the burner body 2 and the inner peripheral side of the outer tube 3.

Further, a first intake passage 71 is formed between the inner peripheral side of the housing 21 and the outer peripheral side of the partition wall 22 so that the intake port 23 communicates with the inner peripheral side of the inner tube 4 and a gas pipe. A second intake passage 72 that communicates with the first intake passage 71 is formed between the outer periphery 20 and the outer peripheral side.
A first exhaust passage 81 through which the combustion gas 102 passes is formed between the outer peripheral side of the inner tube 4 and the inner peripheral side of the outer tube 3.

The radiant tube burner 1 has a heat exchange tube 5 for promoting the exhaust heat recovery. The heat exchange tube 5 is connected in the axial direction of the outer tube 3, and is inserted and disposed on the inner peripheral side of the partition wall 22 so as to cover the outer peripheral side of the inner tube 4.
And by the arrangement of the heat exchange tube 5, a second exhaust passage 82 communicating with the first exhaust passage 81 is formed between the inner peripheral side of the heat exchange tube 5 and the outer peripheral side of the inner tube 4. A third exhaust passage 83 communicating with the exhaust port 24 is formed between the outer peripheral side of the heat exchange tube 5 and the inner peripheral side of the partition wall 22. Further, the heat exchange tube 5 is formed with an exhaust communication gap 51 (see FIG. 3) that connects the second exhaust passage 82 and the third exhaust passage 83.

Further, an exhaust communication gap 51 that connects the second exhaust passage 82 and the third exhaust passage 83 is formed in the heat exchange tube 5. The exhaust communication gap 51 is formed at a part in the circumferential direction of the heat exchange tube 5 at the axial rear end of the heat exchange tube 5. The exhaust communication gap 51 is formed at a position opposite to the exhaust port 24 in the circumferential direction.
A plurality of heat transfer fins 45 are provided on the outer peripheral side of the inner tube 4 except for the vicinity of the rear end portion in the axial direction.
In addition, in this example, an axial direction front-end | tip part means the edge part which faces the direction in which the flame by combustion of the fuel 100 and the combustion air 101 is formed in each part, and an axial rear end part is It refers to the end opposite to the axial tip.

  Then, the radiant tube burner 1 allows the combustion air 101 taken in from the intake port 23 to pass through the first intake passage 71, and flows into the second intake passage 72 from one end of the inner tube 4. It is comprised so that it may burn with the fuel 100 injected from. Further, the radiant tube burner 1 allows the combustion gas 102 that has been burned to pass through the first exhaust passage 81, the second exhaust passage 82, and the third exhaust passage 83 sequentially from the other end of the inner tube 4. The exhaust port 24 is configured to exhaust to the outside of the radiant tube burner 1.

This will be described in detail below.
In this example, as shown in FIGS. 1 and 2, the radiant tube burner 1 is used to heat the atmospheric gas 103 in the heat treatment furnace 6, and the atmospheric gas 103 is brought into direct contact with the combustion gas 102. Heat without. Moreover, the radiant tube burner 1 of this example is used when the temperature of the atmospheric gas 103 in the heat treatment furnace 6 is heated to 500 to 1300 ° C.
Further, the radiant tube 1 of this example is a straight type in which the outer tube 3 and the inner tube 4 have a linear shape.
Moreover, the fuel 100 introduced into the gas pipe 20 is various gaseous fuels other than city gas and LPG.

  As shown in FIGS. 1 and 2, the radiant tube burner 1 of the present example has a cylindrical partition wall 22 inserted and disposed on the inner peripheral side of a cylindrical housing 21, and the heat exchange tube 5 on the inner peripheral side of the partition wall 22. Is inserted and arranged. Further, the radiant tube burner 1 is formed by connecting the outer tube 3 to the distal end portion in the axial direction of the partition wall 22 and inserting the inner tube 4 through the inner peripheral side of the partition wall 22 and the outer tube 3. Further, the radiant tube burner 1 is configured such that a rectifying pipe 25 (described later) is inserted and disposed on the inner peripheral side of the inner tube 4, and a gas pipe 20 is inserted and disposed on the inner peripheral side of the rectifying pipe 25.

The radiant tube burner 1 is fixed to the furnace wall 61 of the heat treatment furnace 6, and the combustion gas 102 produced by the combustion of the fuel 100 and the combustion air 101 is used in the heat treatment furnace 6 with the outer tube 3 as a heat transfer surface. The atmosphere gas 103 is subjected to heat exchange, and the atmosphere gas 103 is heated. The outer tube 3 is fixed to the outer wall surface 611 of the furnace wall 61 by the flange portion 31, and the burner body 2 has a flange portion in a state where the heat exchange tube 5 is detachably disposed therein. 31 is fixed to the outer wall surface 611 of the furnace wall 61 so as to sandwich the 31.
Moreover, the axial direction front-end | tip part in the burner body 2, the partition 22, the inner tube 4, the heat exchange tube 5, etc. is located in the direction inside the furnace of the heat treatment furnace 6, and an axial rear end part is an axial direction front-end | tip part. It is located in the opposite direction.

As shown in FIGS. 1 and 2, an intake pipe 231 for introducing the combustion air 101 into the first intake passage 71 is connected to the housing 21 of this example, and the intake port 23 is connected to the intake pipe. 231 is formed as a portion opening in the housing 21.
Further, an exhaust pipe 241 for exhausting the combustion gas 102 in the third exhaust passage 83 to the outside of the radiant tube burner 1 is connected to the partition wall 22 of this example, and the exhaust port 24 is connected to the exhaust pipe 241. Is formed as a portion opening in the partition wall 22.

The connection portion of the intake pipe 231 to the housing 21 and the connection portion of the exhaust pipe 241 to the partition wall 22 are either a double pipe formed by arranging either the intake pipe 231 or the exhaust pipe 241 on the other inner peripheral side. It has a tube structure. In this example, the connection portion of the intake pipe 231 to the housing 21 is disposed on the inner peripheral side of the connection portion of the exhaust pipe 241 to the partition wall 22. With such a double pipe structure, heat exchange between the combustion air 101 and the combustion gas 102 can be effectively performed between the intake pipe 231 and the exhaust pipe 241.
Further, the connection portion of the intake pipe 231 to the housing 21 (position of the intake port 23) and the connection portion of the exhaust pipe 241 to the partition wall 22 (position of the exhaust port 24) are close to the furnace wall 61 in the burner body 2. It is formed at a site (the axial tip of the burner body 2).

As shown in FIGS. 1 and 3, the exhaust communication gap 51 of this example includes the axial rear end portion of the heat exchange tube 5 and the fixing portion of the inner tube 4 in the burner body 2 (the axial rear end portion of the partition wall 22). Is formed between. The exhaust communication gap 51 of this example is formed by making the rear end surface 511 in the axial direction of the heat exchange tube 5 into an inclined end surface 511 that is inclined with respect to the axial direction of the heat exchange tube 5.
Further, in this example, a portion having the largest axial gap width of the exhaust communication gap 51 formed by the inclined end surface 511 of the heat exchange tube 5 is connected to the partition wall 22 of the exhaust pipe 241 in the circumferential direction of the burner body 2. The connecting portion (the position of the exhaust port 24) is the farthest position (a position approximately 180 ° away from the circumference).
Thus, the exhaust communication gap 51 and the exhaust port 24 are formed at positions farthest from each other in both the axial direction and the circumferential direction of the burner body 2.

Further, the partition wall 22 in the burner body 2 is formed from the tip end portion in the axial direction of the housing 21. The first intake passage 71 is in communication with the second intake passage 72 at the axial rear end of the housing 21.
Further, the flange portion 41 of the inner tube 4 is attached to the axial rear end portion of the partition wall 22, and the gas pipe 20 is fixed to the axial rear end portion of the housing 21.

As shown in FIG. 1, a gas nozzle 201 having a diameter larger than that of the gas pipe 20 is formed at the tip of the gas pipe 20. Further, an ignition rod 202 for igniting an air-fuel mixture of the fuel 100 and the combustion air 101 is disposed on the inner peripheral side of the gas pipe 20.
Further, a rectifying pipe 25 is disposed on the outer peripheral side of the gas pipe 20 so as to cover the gas pipe 20, and the second intake passage 72 of this example is connected to the outer peripheral side of the rectifying pipe 25 and the inner tube 4. Is formed between the inner peripheral side and the inner peripheral side.

  The rectifying pipe 25 is fixed to the rear end portion in the axial direction of the housing 21. The passage cross-sectional area in the second intake passage 72 is reduced by the arrangement of the rectifying pipe 25. Specifically, when the minimum passage sectional area in the second intake passage 72 is D1 and the minimum opening sectional area in the intake port 23 is D2, D1 is 0.5 to 1.1 times larger than D2. Have.

  As shown in FIGS. 1 and 3, the plurality of heat transfer fins 45 in the inner tube 4 of this example are formed from the vicinity of the axial rear end to the position facing the gas nozzle 201 except for the vicinity of the axial rear end. Has been. Further, the rear end in the axial direction of the heat transfer fin 45 is separated from the rear end in the axial direction of the heat exchange tube 5 facing the outer end of the inner tube 4 by a predetermined distance X (10 to 50 mm in this example). It is located in the place. Thus, a gas inflow space 46 is formed in the vicinity of the rear end portion in the axial direction on the outer peripheral side of the inner tube 4 because the heat transfer fins 45 are not provided. Further, the tip of the heat transfer fin 45 in the axial direction is located on the tip side of the tip of the heat exchange tube 5 in the axial direction, and in this example, is located at a position facing the gas nozzle 201.

The outer tube 3 is made of a ceramic material, and the housing 21, the partition wall 22, the gas pipe 20, the inner tube 4, the heat exchange tube 5, and the rectifying pipe 25 are made of a metal material.
The plurality of heat transfer fins 45 in the inner tube 4 are integrally formed with the inner tube 4 as a cast product. The plurality of heat transfer fins 45 include a plurality of plate-like protrusions 45 that are elongated in the axial direction of the burner body 2.
The outer tube 3 can also be formed from a metal material, and the inner tube 4 and the plurality of heat transfer fins 45 can be integrally formed from a ceramic material.

Hereinafter, heating by the radiant tube burner 1 and exhaust heat recovery performed when the combustion gas 102 passes through the exhaust passages 81, 82, 83 will be described.
As shown in FIGS. 1 and 2, first, combustion air 101 is sucked into the burner body 2 from the intake port 23, and the combustion air 101 is passed through the first intake passage 71 and the second intake passage 72. . The mixture of the fuel 100 injected from the gas nozzle 201 in the gas pipe 20 and the combustion air 101 flowing in the inner tube 4 is ignited by the ignition rod 202 to form a flame and burn.

Then, the combustion gas 102 that has performed the combustion flows in the inner tube 4 toward the inside of the heat treatment furnace 6 and collides with the tip 32 of the outer tube 3, and then enters the first exhaust passage 81. Flowing.
Thus, the combustion gas 102 exchanges heat with the atmospheric gas 103 in the heat treatment furnace 6 using the outer tube 3 as a heat transfer surface, and heats the atmospheric gas 103.

Next, the combustion gas 102 flows from the first exhaust passage 81 to the second exhaust passage 82. At this time, the combustion gas 102 passing through the first exhaust passage 81 and the second exhaust passage 82 is for combustion flowing in the second intake passage 72 formed in the inner tube 4 with the inner tube 4 as a heat transfer surface. Heat exchange with the air 101 can be performed to increase the temperature of the combustion air 101 (see FIG. 2). At this time, heat exchange between the combustion gas 102 and the combustion air 101 is further promoted by the plurality of heat transfer fins 45 provided in the inner tube 4, and the exhaust heat recovery efficiency of the combustion gas 102 can be further improved.
Thus, as the first stage exhaust heat recovery, exhaust heat due to the combustion gas 102 flowing through the first exhaust passage 81 and the second exhaust passage 82 can be recovered.

  Further, as described above, the plurality of heat transfer fins 45 are formed up to a position facing the gas nozzle 201 on the outer peripheral side of the inner tube 4, and the combustion air 101 passing through the second intake passage 72 and the first exhaust gas. The distance for heat exchange between the combustion gas 102 passing through the passage 81 and the second exhaust passage 82 can be made as long as possible. Further, as described above, the rectifying pipe 25 is disposed on the outer peripheral side of the gas pipe 20, thereby reducing the cross-sectional area of the second intake passage 72. Therefore, the first stage exhaust heat recovery can be performed more effectively by these devices.

Next, the combustion gas 102 that has been subjected to the first stage exhaust heat recovery flows from the second exhaust passage 82 to the third exhaust passage 83 through the exhaust communication gap 51 provided in the heat exchange tube 5.
When the combustion gas 102 that has been subjected to the first stage exhaust heat recovery passes through the third exhaust passage 83, the combustion gas 102 uses the partition wall 22 of the burner body 2 as a heat transfer surface and the first intake air. Heat exchange is performed with the combustion air 101 flowing through the passage 71, and the temperature of the combustion air 101 can be raised (see FIG. 2). Thus, the exhaust heat from the combustion gas 102 flowing through the third exhaust passage 83 can be recovered as the second stage exhaust heat recovery.
After that, the combustion gas 102 that has been subjected to the second stage exhaust heat recovery is exhausted to the outside of the radiant tube burner 1 through the exhaust port 24.

  Further, when the exhaust heat recovery at the first stage and the second stage is performed, after the combustion gas 102 flowing in the second exhaust passage 82 flows along the heat transfer fins 45, the heat transfer fins 45 are not yet removed. The gas flows into the gas inflow space 46 that is a formation portion, and flows around the outer peripheral side of the inner tube 4 to the exhaust communication gap 51 using the gas inflow space 46. Therefore, the combustion gas 102 flowing in the second exhaust passage 82 along the heat transfer fins 45 immediately flows into the third exhaust passage 83 via the exhaust communication gap 51 after flowing into the gas inflow space 46. it can.

  Thereby, it is possible to prevent the combustion gas 102 from staying more than necessary in the second exhaust passage 82, and the exhaust heat recovery at the first and second stages can be effectively performed. Further, the exhaust communication gap 51 and the exhaust port 24 are formed at positions opposite to each other in the circumferential direction, and the combustion gas 102 passing through the exhaust communication gap 51 is prevented from being immediately exhausted to the exhaust port 24. can do.

Thus, in this example, the heat exchange tube 5 is provided to form the second exhaust passage 82 and the third exhaust passage 83, so that the first exhaust passage 81 is directed to the exhaust port 24. The combustion gas 102 can be made difficult to flow. Then, the exhaust heat recovery efficiency of the combustion gas 102 can be improved by performing the two-stage exhaust heat recovery in a state where the residence time of the combustion gas 102 in the radiant tube burner 1 is increased.
Further, in this example, the exhaust heat recovery efficiency is further improved by devising the formation of the heat transfer fins 45 described above, the formation state of the heat transfer fins 45 and the formation state of the exhaust communication gap 51 in the heat exchange tube 5. Can be made.
Therefore, according to this example, the exhaust heat recovery efficiency of the combustion gas 102 can be improved, and the thermal efficiency in the radiant tube burner 1 can be further improved.

Cross-sectional explanatory drawing which shows the radiant tube burner in an Example. It is a figure which shows the radiant tube burner in an Example, and is AA arrow cross-section explanatory drawing in FIG. Cross-sectional explanatory drawing which shows the periphery of the exhaust communication gap | interval in a heat exchange tube in an Example. Cross-sectional explanatory drawing which shows the radiant tube burner in a prior art example. It is a figure which shows the radiant tube burner in a prior art example, and is AA arrow cross-section explanatory drawing in FIG. It is a figure which shows the radiant tube burner in a prior art example, and is BB arrow sectional explanatory drawing in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radiant tube burner 100 Fuel 101 Combustion air 102 Combustion gas 103 Atmospheric gas 2 Burner body 20 Gas pipe 201 Gas nozzle 21 Housing 22 Bulkhead 23 Intake port 24 Exhaust port 3 Outer tube 4 Inner tube 45 Heat transfer fin 5 Heat exchange tube 51 Exhaust communication Gap 6 Heat treatment furnace 71 First intake passage 72 Second intake passage 81 First exhaust passage 82 Second exhaust passage 83 Third exhaust passage

Claims (2)

A burner body including a cylindrical housing provided with an intake port and an exhaust port, a cylindrical partition wall disposed on the inner peripheral side of the housing, and a gas pipe disposed on the inner peripheral side of the partition wall;
An outer tube disposed on the outer peripheral side of the gas pipe and connected in the axial direction of the burner body;
An inner tube disposed between the gas pipe and the partition wall and the outer tube;
Combustion air taken in from the intake port is passed through a first intake passage formed between the housing and the partition, and is formed between the inner tube and the gas pipe from one end of the inner tube. The fuel is injected into the second intake passage and burned together with the fuel injected from the gas pipe, and the burned combustion gas is formed between the inner tube and the outer tube from the other end of the inner tube. In the radiant tube burner configured to pass through the first exhaust passage and lead to the exhaust port,
A heat exchange tube is disposed between the partition wall and the inner tube so as to be connected in the axial direction of the outer tube, and communicated with the first exhaust passage between the heat exchange tube and the inner tube. Forming a second exhaust passage, and forming a third exhaust passage communicating with the exhaust port between the heat exchange tube and the partition wall,
The heat exchange tube is formed with an exhaust communication gap that communicates the second exhaust passage and the third exhaust passage, and the exhaust communication gap is formed at the axial rear end of the heat exchange tube. It is formed in a part in the circumferential direction of the heat exchange tube, and is formed at a position opposite to the exhaust port,
A radiant tube burner, wherein a plurality of heat transfer fins are provided on the outer peripheral side of the inner tube except for the vicinity of the rear end portion in the axial direction thereof. In claim 1, a gas nozzle having a diameter larger than that of the gas pipe is formed at an axial tip of the gas pipe.
The radiant tube burner characterized in that the tip of the heat transfer fin in the inner tube is located near the position facing the gas nozzle.

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